The present invention relates to methods and apparatus for printing a graphic product on sheet material in accordance with a printing program and stored data representative of the graphic product, and more particularly to methods and apparatus for printing a wide format multicolor graphic product on a printing sheet, such as a vinyl sheet for use as signage.
Known in the art are thermal printing apparatus for generating signs, designs, characters and other graphic products on a printing sheet in accordance with a printing program and data representative of the graphic product. Typically, a thermal printer interposes a donor sheet that includes donor material and a backing between a thermal printhead and the printing sheet. The thermal printhead includes an array of thermal printing elements. The thermal printhead prints by pressing the donor sheet against the printing sheet and selectively energizing the thermal printing elements of the array, thereby selectively transferring pixels of donor medium from the donor sheet to the printing sheet. Movement of the printing sheet relative to the thermal printhead (or vice versa) while pressing the donor sheet against the printing sheet with the thermal printhead draws fresh donor sheet past the thermal printhead. The printing sheet typically includes a vinyl layer secured to a backing layer by a pressure sensitive adhesive so that after printing the vinyl bearing the graphic product can be cut and stripped from the backing material and affixed to an appropriate sign board or other material for display.
The proper printing of many graphic products, such as commercial artwork or signage, can require high quality print work. Often, it is desired that the final multicolor graphic product be physically large, such as several feet wide by tens of feet long. Typically, existing thermal printers are limited in the width of printing sheet that they can print upon. For example, one popular thermal printer prints on sheets that are one foot wide. Accordingly, the final graphic product is often assembled from separately printed strips of printing sheet that must be secured to the signboard in proper registration with one another. Often, the registration is less than perfect and the quality of the final graphic product suffers, especially when backlit.
Wide format thermal printers are known in the art. For example, one wide format thermal printer currently available can accommodate a printing sheet up to three feet wide and uses four full width (i.e., three feet wide) printheads, each interposing a different color donor sheet between the printhead and the printing sheet. Accordingly, far fewer seams, if any at all, require alignment when creating the sign or other product. Also, the use of four printheads allows faster printing of the multicolor graphic product.
Unfortunately this type of machine can be expensive to manufacture and to operate. For example, each printhead, at a typical resolution of 300 dpi, includes literally thousands of thermal printing elements, all of which are typically required to have resistances that are within a narrow tolerance range. Such a thermal printhead is difficult and expensive to manufacture, and moreover, burnout of simply a few thermal printing elements can require replacement of the entire printhead. Furthermore, donor sheet is also expensive, and the full-width printing heads can be wasteful of donor sheet when printing certain types of, or certain sections of, graphic products. For example, consider that a single color stripe one inch wide and perhaps a foot long is to be printed in center of the printing sheet. Though the printed object occupies {fraction (1/12)} of a square foot, an area of donor sheet that is three feet wide by one foot long, or three square feet, is transferred past the print head when printing the above object, and hence consumed. The printing of a wide format graphic product that includes a narrow border about the periphery of the printing sheet is another example that typically can be wasteful of donor sheet when printing with the above wide format thermal printer.
Other wide format printers are known in the art, such as wide format inkjet printers, which can also print in a single pass. However, inkjet printed multicolor graphic products are typically not stable when exposed to the elements (e.g., wind, sun, rain) or require special post-printing treatment to enhance their stability, adding to the cost and complexity of printing with such apparatus.
Accordingly, it is an object of the present invention to address one or more of the foregoing and other deficiencies and disadvantages of the prior art.
Other objects will in part appear hereinafter and in part be apparent to one of ordinary skill in light of the following disclosure, including the claims.
In one aspect, the invention provides an assembly providing a supply of donor sheet for use in a printing operation and for replaceable use with a donor sheet cassette. The assembly includes a core having a tubular body, which body extends along a longitudinal axis between a base end and a drive end, and which body also has a central opening extending along the longitudinal axis between the base end and the drive end and a selected length of donor sheet wound about the core body. The core body also includes a plurality of drive elements, which drive elements extend along and radially of the longitudinal axis, and are located within the central opening substantially at the drive end of the core body. The assembly further includes a memory element mounted within the central opening of the core body and substantially at the drive end of the core body and inboard of the drive elements, the memory element having a data transfer face substantially perpendicular to the longitudinal axis and facing the base end of the core body and a back face facing the drive end of the core body.
The assembly can also include a take-up core having a tubular body, which body extends along a longitudinal axis between a base end and a drive end, and which body also has a central opening extending along the longitudinal axis between the base end and the drive end of the core body. The take-up core can also include a plurality of drive elements, which drive elements extend along and radially of the longitudinal axis, and are located within the central opening substantially at the drive end of the core body and are substantially identical to the drive elements of the supply core body. The free end of the length of donor sheet is coupled to the take-up core body.
In an additional aspect of the invention, there is provided an assembly for providing a supply of donor sheet for use with a wide format thermal printer for printing a multicolor graphic product onto a printing sheet in separate color planes. The assembly is for replaceable insertion in a refillable donor sheet cassette, where the cassette replaceably mounts on a cassette receiving station mounted with a thermal printhead of the thermal printer, and the cassette receiving station is adapted for receiving the cassette such that a section of donor sheet is positioned under the thermal printhead and interposed between the printhead and the printing sheet when printing. The assembly includes a core having a tubular body, which body extends along a longitudinal axis between a base end and a drive end, and which body also has a central opening extending along the longitudinal axis between the base end and the drive end and a selected length of donor sheet wound about the core body. The core body includes a plurality of drive elements, which drive elements extend along and radially of the longitudinal axis, and are located within the central opening substantially at the drive end of the core body. A memory element mounts within the central opening of the core body and substantially at the drive end of the core body and inboard of the drive elements. The memory element includes a data transfer face substantially perpendicular to the longitudinal axis and facing the base end of the core body and a back face facing the drive end of the core body.
In yet another aspect, the invention provides a method of providing a replaceable donor sheet assembly for insertion in a refillable cassette and for use with a thermal printer for providing a donor sheet for thermal printing. The method includes the steps of providing a length of donor sheet; providing a core having a tubular body extending along a longitudinal axis between a base end and a drive end and having a central opening extending therethrough between the base and drive ends, where the core includes a plurality of drive elements, which drive elements extend along and radially of the longitudinal axis and are located within the central opening substantially at the drive end of the core body, as well as a memory element mounted within the central opening of the core body and substantially at the drive end of the core body and inboard of the drive elements, where the memory includes a data transfer face substantially perpendicular to the longitudinal axis and facing the base end of the core body and a back face facing the drive end of the core body; winding the selected length of the donor sheet about the core body; determining selected data characteristic of the donor sheet; and writing the selected data to the memory element.
In yet another aspect of the invention, there is provided a method of manufacturing a replaceable assembly for providing a supply of donor sheet and for insertion in a refillable cassette. The method includes the steps of: providing a length of donor sheet having a first width W; cutting the length of donor sheet along its length into N separate slice lengths of donor sheet each having a width approximately equal to W divided by N; providing N supply core bodies; winding the N slice lengths of donor sheet onto the N core bodies to provide N wound supply core bodies of donor sheet; providing N memory elements each having data transfer and back faces, each of the memory elements mounted within a different supply core body substantially at a first end thereof and having the data transfer face facing inwardly toward the second end of the core body; testing the donor sheet to determine data characteristic of the donor sheet; storing on the memory elements the data characteristic of the sheet material; providing N take-up core bodies; and affixing free ends of each of the slice lengths wound on the supply core bodies to a different take-up core body to form N donor sheet assemblies.